13 R 15 is a 2013 redemption and is the 15th kart made
12 R 174 is a 2012 Redemption and the 174th kart made.
The spindle degrees are stamped directly on the spindle arm. Ex. Lf spindles will have a 3, 5, 8, 0 meaning it has a 3 degree, 5degree, 8 degree, or 10 degree spindle.
The rf spindles if I remember correctly are marked with a V which is the latest spindle marc has put on the karts. Meaning same spindle since the Voodoo, i think that is correct or the new spindles arent stamped. But im pretty sure they are. Or J for a joker spindle etc.